Hyper ig d syndrome

Hyper IgD Syndrome

Prof Ariyanto Harsono MD PhD SpA(K)

Introduction

Hyperimmunoglobulinaemia D with periodic fever syndrome is more commonly known as hyper-IgD syndrome or HIDS. It is a rare inherited autoinflammatory syndrome that presents with recurrent episodes of fever, skin rash, abdominal pain, headaches and enlarged lymph glands that begin in infancy.

Mevalonic aciduria is a severe variant of HIDS.

2Prof Ariyanto Harsono MD PhD SpA(K)

Keywords: higds, mevalonate kinase, IL1, inborn error of metebolism, recurrent fever

Hyper-IgD syndrome is a rare autosomal recessive disorder in which recurring attacks of chills and fever begin during the first year of life. Episodes usually last 4 to 6 days and may be triggered by physiologic stress, such as vaccination or minor trauma.

Hyper-IgD syndrome clusters in children of Dutch, French, and other Northern European ancestry and is caused by mutations in the gene coding mevalonate kinase, an enzyme important for cholesterol synthesis. Reduction in the synthesis of anti-inflammatory isoprenylated proteins may account for the clinical syndrome.


Etiology

Virtually all patients with the syndrome have mutations in the gene for mevalonate kinase, which is part of the HMG-CoA reductasepathway, an important cellular metabolic pathway. Indeed, similar fever attacks (but normal IgD) have been described in patients with mevalonic aciduria - an inborn error of metabolism now seen as a severe form of HIDS.


PathophisiologyThe hyper-IgD syndrome is caused by mutations in the

gene encoding mevalonate kinase (MVK)

In addition to HMG-CoA reductase, mevalonate kinaseis involved in the biosynthesis of cholesterol and isoprenoids, and catalyses the conversion of mevalonate to 5-phospho mevalonic acid in the mevalonate metabolism. The enzyme mevalonatekinase is involved in the isoprenoid pathway of cholesterol biosynthesis. The enzyme deficiency results accumulation of mevalonic acid and increased interleukin 1. The mechanism of mevalonate kinasedeficiency to cause hyper IgD is not kown.


It is not known how mevalonate kinase mutations cause the febrile episodes, although it is presumed that other products of the cholesterol biosynthesis pathyway, the prenylation chains (geranylgeraniol and farnesol) might play a role.

Prof Ariyanto Harsono MD PhD SpA(K) 6

Immunoglobulins are proteins produced by certain white blood cells. There are five classes of immunoglobulins known as IgA, IgD, IgE, IgG, and IgM. Immunoglobulins play a role in defending the body against foreign substances or microorganisms by destroying them or coating them so they are more easily destroyed by white blood cells. While the specific function of other immunoglobulins is well-known, the specific function of IgD within the immune system is unknown.


Clinical SymptomsIn addition to chills and fever, patients may have:

abdominal pain,

vomiting or diarrhea,

headache, and

arthralgias.

Signs include cervical lymphadenopathy, splenomegaly, arthritis, skin lesions (maculopapular rash, petechiae, or purpura), and orogenital aphthous ulcers


Cutaneous signs of HIDSo Skin rash affects up to 80% of patients. A number of skin eruptions or rashes

have been described in this syndrome, and these resolve slowly after the febrile episode settles.

The rashes seen in HIDS are most commonly described as follows: small flat spots (macules) raised bumps (small papules or larger nodules) measles-like rash (morbilliform) hive-like rash (urticarial). Less common or rare skin presentations include: Henoch-Schönlein purpura erythema elevatum diutinum petechiae (tiny bleeding spots or purpura) erythema nodosum.

o Oral and/or vaginal aphthous ulcers affect 50% of patients.


Symptom Features

Fever over 40C

preceding chills and malaise

Skin rash affects up to 80%

various presentations (see below)

Headache nonspecific

Enlarged lymph nodes in neck characteristic

bilateral

painful

Abdominal pain severe

diarrhoea and vomiting

peritonitis

Joint pain arthralgia (pain) or arthritis (swelling)

most common in young patients

affects large joints

symmetrical, polyarticular, non-destructive

symptoms occur with abdominal pain and settle slowly

Enlarged liver and spleen (hepatosplenomegaly) affects 50% of children

Tendonitis

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Trigger

Acute episodes may be triggered by:

o Vaccinations – more than 50% report at least one episode in childhood following an immunisation

o Infection

o Physical and emotional stress

o Trauma, including surgery


Diagnosis

The characteristic recurrent acute febrile attacks without a clear infectious or autoimmune cause, suggest the need for investigation.

Clinical criteriaIn addition to the the of febrile attacks outlined above,

clinical diagnostic criteria should include:o Onset before the age of 5 yearso Episodes last less than 14 dayso MVK gene mutations are unlikely if these features are

not present.


IgD levels

Raised levels of IgD can be found in many but not all patients, especially in children under 3 years of age. Levels are raised not only during an attack but between attacks. Elevations of IgD levels can occur in other periodic fever syndromes such as familial Mediterranean fever and TRAPS, and other chronic inflammatory conditions, so it should be interpreted with caution.


Other useful tests

o Urine organic acids measured during an acute attack usually show raised levels of mevalonic acid.

o During an attack:

leukocytosis,

Increase erythrocyte sedimentation rate (ESR),

increaseC-reactive protein (CRP) and serum amyloid A (SAA).

Serum IgA levels may also be increased.

o Radiometric assay testing can demonstrate reduced mevalonate kinase activity in white blood cells or cultured fibroblasts.

o Skin biopsy may show a mild vasculitis which may extend deeply. Changes may resemble Sweet disease or cellulitis.


DNA analysisDNA analysis showing two disease-linked mutations in the MVK gene is used to confirm the diagnosis of HIDS. In most cases the patient has two different mutations, called compound heterozygosity.


Treatment of HIDS

Many treatments have been tried in HIDS, none with uniform success:

Colchicine – is generally unhelpful although there are case reports of its successful use

Non-steroidal anti-inflammatory drugs (NSAID)

Statins – such as simvastatin, inhibit HMGCoA-reductaseresulting in reduced production of mevalonic acid

Systemic corticosteroids – a single dose at the start of an attack may reduce the severity and duration (1mg/kg)


Dapsone

Ciclosporin

Thalidomide

Intravenous immunoglobulin (IVIG)

Biologic agents– including anakinra (interleukin-1 receptor antagonist) and etanercept (tumournecrosis factor alfa inhibitor) have been reported to reduce the frequency and/or severity of attacks in 80%. However there have also been cases where these agents have increased the frequency and/or prolonged attacks.


Prognosis

There is a tendency to improve with age, with less frequent and less severe attacks by adulthood. Between episodes, health is normal.

A small subgroup of affected patients develop neurologic abnormalities in adulthood, similar to mevalonic aciduria.

Unlike familial Mediterranean fever, amyloidosisis rarely seen in HIDS, affecting less than 3%.

Life expectancy is usually normal, however this can be affected by renal failure due to amyloidosis or severe infections.


Mevalonic aciduria

Mevalonic aciduria involves the same gene and enzyme as HIDS, however the resulting enzyme deficiency is virtually complete. The condition is also called mevalonate kinase deficiency. The gene mutations so far identified have been localised to one end of the enzyme. Mevalonic aciduria results in neurological effects that mainly arise because of inadequate cholesterol, which is required for brain and nerve development.


Patients with mevalonic aciduria suffer the same febrile episodes as in HIDS, but in addition develop profound developmental delay, retinal dystrophy (visual defects) and cataracts, mild facial deformities, and liver/spleen enlargement. Those less severely affected have mental retardation, failure to thrive, progressive cerebellar ataxia (unsteadiness) and anaemia. In childhood and adolescence, eye problems develop, including cataracts and uveitis. Myopathy(muscle weakness) can occur. In those severely affected, mevalonic aciduria is commonly fatal in infancy/childhood.


High levels of mevalonic acid are detected in the urine at all times.

Genetic counselling should be performed for families with an affected child and prenatal testing should be considered.


Periodic fever syndromes


Periodic fever syndromes are conditions in which the patient experiences recurrent episodes of fever with associated inflammatory symptoms, in the absence of infection, allergy, malignancy, immunodeficiency or autoimmune conditions. They are one category of autoinflammatory syndromes.Familial Mediterranean fever (FMF) is the most common and best known of the hereditary periodic fever syndromes. Inherited (genetic) forms of periodic fever syndromes are also known as hereditary recurrent fever syndromes. Nonfamilial syndromes have also been described.


Periodic fever syndromes can be genetic conditions. Therefore some periodic fever syndromes are seen predominantly in specific racial groups. Familial Mediterranean fever, for example, affects races originating from around the eastern Mediterranean area.

The hereditary periodic fever syndromes can be classified by the type of inheritance:

Autosomal recessive

Autosomal dominant


Autosomal recessive periodic fever syndromesGenetic conditions with this type of inheritance require two copies of the abnormal gene; one copy inherited from each parent. Although the defective gene is usually the same in each parent, the actual mutation may be different, i.e., heterogeneous homozygotes or compound heterozygotes. The parents are asymptomatic carriers of the defect.Autosomal recessive periodic fever syndromes with skin involvement include: Familial Mediterranean fever (FMF) Hyperimmunoglobulinaemia D syndrome (hyperIgD

syndrome, HIDS)


Autosomal dominant periodic fever syndromesOnly a single copy of the defective gene is required to develop symptoms and signs of an autosomal dominant periodic fever syndrome. Therefore the condition is usually inherited from an affected parent or, less commonly, is due to a spontaneous mutation in the affected child.Autosomal dominant periodic fever syndromes with skin involvement include: Tumour necrosis factor receptor-associated periodic fever

(TRAPS) Cryopyrin-associated periodic syndromes (CAPS) Familial cold autoinflammatory syndrome (FCAS) Muckle-Wells syndrome (MWS)


Molecular biology of periodic fever syndromes

The defective gene has been identified for these hereditary periodic fever syndromes. The defective gene is different for each of the syndromes with the exception being the three clinically distinct syndromes that are now clustered as the cryopyrin-associated periodic syndromes (CAPS).

All periodic fever syndromes result in overstimulation of the innate immune system, usually due to over-activity of interleukin 1.


Nonhereditary periodic fever syndromes with skin involvement include:

PFAPA syndrome

Schnitzler syndrome

The cause of these syndromes is not yet known.


Symptoms

The one clinical feature in common between all the periodic fever syndromes is the recurrent episodes of fever in the absence of infection, autoimmune disease or malignancy.The frequency of febrile attacks can vary between individuals and syndromes from daily to once every ten years. The duration of the fever during an attak may be hours or be virtually continuous, but is usually typical for a particular syndrome. The height of the fever may range from a slight elevation of temperature to over 40 degrees Celsius.


The age at which the febrile attacks begin is also highly variable between the different syndromes with some beginning at or shortly after birth but others being delayed even as late as middle age.

In some periodic fever syndromes there are well-recognised triggers for a febrile attack, such as generalised exposure to cold triggering a fever infamilial cold autoinflammatory syndrome (FCAS) But in others no trigger is identified.


Most periodic fever syndromes have associated symptoms and signs of inflammation at the same time as the fever. Commonly these affect the serosalsurfaces, joints, eyes and skin. In some forms the predominant associated symptom is severe abdominal pain often leading to unnecessary exploratory surgery. In others, joint or neurological involvement can result in major disability.


Quality of life can be severely impacted, particularly if febrile attacks are frequent or in those forms of periodic fever syndrome that develop joint or neurological complications.

Secondary systemic amyloidosis develops in some periodic fever syndromes and this can result in life-threatening complications.


Diagnosis

Periodic fever syndromes should be suspected clinically when the patient presents with recurrent episodes of fever associated with other inflammatory symptoms. However this can be difficult if the attacks are very infrequent, such once every few years, or continuous. A family history of such episodes is not always present, but is helpful if known.


Periodic fever syndromes can only be considered after infections, allergies, malignancy, immunodeficiencies and autoimmune diseases are excluded.

In children, it can be difficult to distinguish hereditary periodic fevers from the much commoner PFAPA syndrome as there are overlapping clinical features. The Gaslini score may help identify those most likely to benefit from genetic testing, and then to determine the order in which genes should be sequenced.


Some specific periodic fever syndromes can be diagnosed on biochemical testing or challenge with the known trigger. An example of the former is HIDS, which typically is associated with a very high level of IgD in the blood. Triggering of an attack within hours of generalised exposure to cold in FCAS is an example of the latter category.


Genetic testing is often definitive if positive, but not all mutations are known or easily tested for. A negative test does not exclude the diagnosis. In these cases, the diagnosis must be reached on clinical criteria. Genetic testing of the MEFV, TNFRSF1A and MVK genes detects a mutation in 20% of patients with clinical symptoms suggestive of a periodic fever syndrome.


A rapid and complete response to a trial of therapy may support the clinical diagnosis. Familial Mediterranean fever (FMF) responds to colchicine in over 90% of cases. Interleukin-1 blockade with biologic agents results in dramatic resolution of symptoms within hours of the first injection in some specific syndromes.


TreatmentAcute attacks of hereditary periodic fever syndromes are usually treated with bed rest, anti-inflammatory agents, analgesics and sometimes systemic corticosteroids. The fever does not respond to aspirin or paracetamol.

Avoidance of triggers, where known, can reduce the frequency of attacks. Sufferers of familial cold-associated syndrome (FCAS) often move to temperate climates to avoid cold winters and hot summers, for example.


To prevent febrile episodes, improve quality of life and minimise longterm complications, continuous treatment may be required for some forms. Apart from colchicine for familial Mediterranean fever, treatment of the hereditary periodic fever syndromes is with biologic agents such as anakinra, given by subcutaneous injection. Treatment should be started as early as possible to prevent the development of life-threatening complications in such periodic fever syndromes.


Autoinflammatory syndromes


Autoinflammatory syndromes are defined as conditions caused by an exaggerated innate immune system response resulting in episodes of spontaneous inflammation affecting multiple organs. An autoinflammatory syndrome can only be diagnosed when infective conditions, malignancy, allergic and immunodeficiency conditions have been excluded. Compared to classical autoimmune diseases, autoinflammatory syndromes lack pathogenic autoantibodies and antigen-specific T cells.


Classification of autoinflammatory syndromes

Autoinflammatory syndromes may be inherited through mutations to a single gene (monogenic autoinflammatory syndromes), or, more commonly, are polygenic immune conditions that resemble autoimmune collagen disorders. The number of conditions included is increasing as molecular and genetic studies reveal disease mechanisms.

A classification system, with examples of syndromes with dermatologic manifestations, follows.


Hereditary fever syndromes

Familial Mediterranean fever (FMF)

Tumour necrosis factor receptor-associated periodic fever syndrome (TRAPS)

Hyper-IgD syndrome (HIDS)


Other monogenic autoinflammatory syndromes Cryopyrin-associated periodic syndromes (CAPS)

o Familial cold autoinflammatory syndrome ( FCAS)o Muckle-Wells syndrome (MWS)o Neonatal onset multisystem inflammatory disease/chronic

Infantile neurologic cutaneous arthropathy syndrome (NOMID/CINCA)

Syndrome of pyogenic arthritis, pyoderma gangrenosumand acne (PAPA syndrome, PAPAS, PAPGA syndrome)

Juvenile systemic granulomatosis (Blau syndrome, early onset sarcoidosis)

Deficiency of interleukin-1 receptor antagonist (DIRA)Mevalonic aciduriaMajeed syndrome


Nonhereditary or polygenic disorders

Schnitzler syndrome

Crohn disease

Behcet disease

Psoriatic arthritis

Syndrome of periodic fever, aphthous stomatitis, pharyngitis and adenitis (PAPAS, PFAPA syndrome)Systemic-onset juvenile idiopathic arthritis

Adult-onset Still disease


Treatment

Treatment varies with the actual syndrome. In many forms, systemic corticosteroids have only a modest effect. Biologic agents such as anakinra (which targets IL-1) result in a dramatic and consistent improvement in those syndromes where a clear link to IL-1 has been shown. There is less consistent benefit in other conditions where a direct link with IL-1 has not been found.


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Hyper ig d syndrome